Generally, a medical solution container must meet a number of performance criteria, including flexibility, transparency, gas barrier property, drug compatibility, heat sterilization resistance, fall impact resistance, etc.
As the medical solution container, it is common used a flexible plastic bag with multiple chambers (two and more) divided by partition walls. The medical solution container uses partition wall for various medical solutions kept in each chambers not to react with other medical solution kept in other chambers. And when the medical solution is in need to inject to a patient, the medical solution is mixed by pushing the chambers for various medical solutions to be mixed. The mixed functional medical solutions are administered to a patent via spike port using a syringe with sanitary and safe.
In case of administering medical solutions by connecting a few or many medical solution bags or bottles, medical staff may mistake in injecting medical solution, but using the afore-mentioned medical solutions having chambers divided by partition walls reduce the mistake by medical staff and gives various merits in keeping and handling.
Various types of medical solution container are now available, for example, a double bag with an inner bag and outer bag, where the inner bag contains functional medical solutions and the outer bag covers the inner bag and has gas or oxygen blockage function.
In this way, medical solution container having multiple chambers or single inner bag wrapped by outer bag have been studied from 10 years ago in Europe, and recently investigation for building up properties, i.e. fall impact resistance as well as gas or moisture barrier function are accelerated.
In general, the inner bag needs to have various properties such as oxygen and moisture barrier property, heat sterilization resistance, transparency, fall impact resistance, flexibility, etc, and the outer bag also needs to have various properties such as oxygen and moisture barrier property, heat sterilization resistance, and transparency, etc rather than fall impact resistance and flexibility.
In especial, the container for medical solutions, i.e. functional medical solutions, should have superior gas barrier property, fall impact resistance and transparency in comparison with that of a conventional medical solution container. Preferably, the film with high transparency for an outer bag is necessary in order to check impurities in functional medical solutions. In addition to this, it is required to new film manufacturing technology for guarantee transparency after sterilization of 121° C. Also, the outer bag must have high oxygen barrier property, because various medical solutions to be able to react with oxygen are wrapped in the inner bag.
The product of Pactive. Ltd in Germany, one of the best outer bags, is a multilayer (5 layers) co-extruded film laminated a PP outer layer/polyolefin adhesive layer/EVOH oxygen barrier intermediate layer/polyolefin adhesive layer/PP heat seal layer. Because the product of Pactiv exhibits extremely poor hazes, namely, the haze after sterilization (121° C., 30 minutes) over 50%, it is required to improve transparency for checking impurities in a bag.
To improve transparency, various types of the multilayer film were proposed for example, inorganic oxides deposited on PET, nylon, polyolefin for use in the fields of foods and medical industries.
Japanese Patent laid-open 2000-263722 suggests a multilayer film having improved barrier property to oxygen and moisture by laminating PET film on PP base film and depositing metal oxide like silica or alumina on the PET film.
PCT publication WO 2007/026554 describes a method of making a barrier film deposited silicon oxide thereon at least one surface of inner or outer surface by plasma CVD with gaseous organic silica compound and oxygen gas.
The above-mentioned material of the multilayer film exhibits poor flexibility, but high barrier property. However, the multilayer film itself has a disadvantage of lessening oxygen barrier property by cracking a deposited inorganic layer caused by repeated folding and unfolding of bag during handling or before and after sterilization.
In especial, the medical solution container bag must have high oxygen barrier property, because injected amino acid solution, glucose solution, and electrolytes degenerate easily by oxygen. The polyolefin inner bag as a medical solution container has low oxygen barrier property, so that extra outer packing or new composition for enhancing oxygen barrier property of the inner bag is necessary.
PCT publication WO 2002/85111 discloses a container having a multilayer laminated structure of a contacting layer/an oxygen and moisture barrier layer/an outer layer, and wherein EVOH was engaged as the oxygen and moisture barrier layer.
PCT publication WO 2005/014283 describes a method of enhancing oxygen barrier property by film structure of LDPE film/a functional barrier layer selected from the group consisting of polyamide, EVOH, PET, blends thereof and aluminum foil/a heat-adhesion layer having inorganic fillers and polyolefin.
However, EVOH has extremely poor haze after sterilization, especially getting worse at the condition of high temperature and moisture, resulting decrease of oxygen barrier property.
Therefore film having superior transparency despite high temperature treatment and oxygen barrier property is necessary, and the present invention proposes the multilayer film having satisfactory transparency and oxygen barrier property that can overcome the above-mentioned various problems.